The vast majority of balers do not have their own engine, but are towed by a tractor, and is are powered by coupling the power take-off (PTO) shaft of the tractor to an input shaft of the baler. The balers further have a flywheel connected to the input shaft, and a gearbox that drives the various mechanisms in the baler to pick-up the crop from a field, to form the crop into bales and to wrap twine and/or foil around the bales.
A one-way clutch is typically arranged between the PTO shaft and the flywheel to allow the flywheel to rotate faster than the PTO shaft. The baler input shaft can be operatively decoupled from the tractor PTO, e.g. for transportation of the baler from one field to the other.
A large and heavy flywheel is typically required in a baler, especially in so called “large square balers”, or “high density balers” to overcome peak loads encountered by the baler gearbox, which occurs e.g. when the plunger of the baler compresses the crop material in the bale chamber when forming the bales. By using a flywheel with a high inertia and running at a high speed (e.g. 1000 rpm), peak energy for the peak loads can be delivered by the flywheel, which slightly slows down during each compression, and which is accelerated again by the tractor PTO between two compressions.
When all the crop material of one field is processed, the baler is shut down for safety reasons before being transported to another field. When the baler (i.e. the flywheel and the various mechanisms connected thereto) has come to a stop, it is known in the art to keep the flywheel (and the various mechanisms along with it) in a fixed position by using a belt which is tensioned around a section of the flywheel.
It is important to keep the flywheel in a fixed position during transport, because objects or people wearing loose clothing that may come too close to the baler might get caught in the moving parts. This is especially important with heavy flywheels (e.g. 700 kg) and heavy crank arms (e.g. 150 kg), which may cause the flywheel to turn under their weight, or due to acceleration or deceleration of the tractor, or inclination of the road.
It may be even more important to keep the flywheel in a fixed position when an operator is working on the baler, e.g. during maintenance or repair.
As the flywheel becomes larger and heavier, the belt and fastener do not guarantee sufficient safety anymore. Moreover, improper handling of the belt can cause dangerous situations.